This list is a categorization of the most common food components based on their macronutrients. Macronutrients can refer to the chemical substances that humans consume in the largest quantities (See Nutrient) Macronutrients that provide energy There are three principal classes of macronutrients: carbohydrate, protein, and fat. Macronutrients are defined as a class of chemical compounds which humans consume in relatively large quantities compared to vitamins and minerals, and which provide humans with energy. Fat has a food energy content of and proteins and carbohydrates . Water makes up a large proportion of the total mass ingested as part of a normal diet, but it does not provide any nutritional value. Ethanol provides calories, but there is no requirement for ethanol as an essential nutrient. Carbohydrates Glucose Sucrose Ribose Amylose (a major component of starch) Amylopectin Maltose Galactose Fructose Lactose Protein Essential and non-essential amino acids Alanine Arginine Aspartic acid (aspartate) Asparagine Cysteine Glutamic acid (glutamate) Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine Fats Saturated (i.e., stable) fatty acids Acetic acid (C2) Propionic acid (C3) Butyric acid (C4) Valeric acid (C5) Caproic acid (C6) Caprylic acid (C8) Capric acid (C10) Lauric acid (C12) Myristic acid (C14) Pentadecanoic acid (C15) Palmitic acid (C16) Margaric acid (C17) Stearic acid (C18) Arachidic acid (C20) Behenic acid (C22) Lignoceric acid (C24) Cerotic acid (C26) Monounsaturated (i.e., semi-stable) fatty acids Myristoleic acid Oleic acid Eicosenoic acids Erucic acid Nervonic acid Polyunsaturated (i.e., unstable) fatty acids Linoleic acid (LA) - an essential fatty acid α-Linolenic acid (ALA) - an essential fatty acid Stearidonic acid (SDA) Gamma-Linolenic acid (GLA) Arachidonic acid (AA) Eicosatetraenoic acid (ETA) Timnodonic acid (EPA) Clupanodonic acid (DPA) Cervonic acid (DHA) Essential fatty acids α-Linolenic acid ALA (18:3) omega-3 fatty acid Linoleic acid LA (18:2) omega-6 fatty acid Macronutrients that do not provide energy Oxygen Oxygen is essential for life. Water Water is also essential for life. It provides the medium in which all metabolic processes proceed. It is necessary for the absorption of macronutrients and micronutrients, but it provides no nutritional energy. Fiber Dietary fiber from fruits, vegetables and grain foods. Insoluble dietary fiber is not absorbed in the human digestive tract, but is important in maintaining the bulk of a bowel movement to avoid constipation. Soluble fiber can be metabolized by bacteria residing in the large intestine. Soluble fiber is marketed as serving a prebiotic function